1. Field of the Invention
This invention relates to a load lashing device with tensioner for use on a freight carrier for use with belts, bands, etc., with two components held at a variable distance from one another by means of a compression spring, as a function of the tensile stress. The two components, guided longitudinally and interlocked, enclose the compression spring between them.
Belts, bands, and similar clamping and lashing means are used in various operations to protect loads during transport. To provide sufficient protection against slipping or sliding of the load under the forces exerted on it during transport, as a function of the load weights and specified physical values, e.g., the coefficient of friction between the loading surface and the item being transported, the calculated gripping power or safety forces of the clamping or lashing means can be retained when the load is lashed down, obliquely or diagonally.
2. Description of the Prior Art
Appropriate calculation methods are described, for example, in the publication "Ladungs-Sicherung leicht gemacht" (Load Protection Made Easy), by H. Dantzer and H. Volkers, which appeared in October 1986 in the Wirtschaftsverlag NW, Verlag fuer neue Wissenschaft GmbH, Bremerhaven.
To meet the requirement of maintaining specified tensile stresses or safety forces on clamping or lashing means, such as belts and bands, it is necessary to have means to measure tensile stress forces. The prior art includes so-called ratchet spanners, by means of which the required tensile stresses can be both applied and measured in orders of magnitude from 100 up to several thousand kiloponds or daN.
To check the load or initial tension of clamping or lashing means, the prior art also includes so-called tension indicators.
For example, the German utility model 82 15 729.4 describes an apparatus to measure and indicate the tensile stress on clamping or lashing means, in particular lashing straps and cables, with a cylinder and at least one spring located therein. The apparatus of the prior art has, as the spring element, a disk spring or a packet of disk springs, which are braced against an abutment rigidly attached to the cylinder. The spring is pierced by a rod projecting out of the cylinder and the spring is engaged by the rod at the back. An indicator for the tensile stress is connected to the rod.
The disk spring packet is disadvantageous as a result of its short length, high load and limited dimensions. The result of such a configuration is a spring with a very steep load deformation curve and high spring constant C. This results in an extremely short travel of the spring system, with indications which are very imprecise and/or difficult to read.
The bolts running through the spring packet, which support a tensile load, also represent a significant safety risk, because they have a threaded portion at the articulated end of the lashing strap, and consequently have a weak point which is severely weakened by a reduction of fatigue strength and is therefore more likely to break. Such weak points can cause failures when extreme loads are exerted frequently.
The apparatus of the prior art therefore does not satisfactorily comply with the recognized rules of the art, in particular in terms of an apparatus which serves a safety function.
Another apparatus of the prior art with a ratchet to brace clamping or lashing means and an integrated initial tension indicator is described in Laid Open German Patent Application 33 46 755. In it the initial stress indicator can be displaced against an elastic force on at least one, and preferably two guides. Depending on the embodiment selected, in particular as shown in FIGS. 2 and 3, the force is introduced by means of a suspended part 79 and is transmitted by means of the initial tension indicator apparatus 39 to the body 60 of the apparatus by means of the compression springs 54. A load moment is thereby exerted on the guides 47, 48, and has an extraordinarily unfavorable effect on the sliding behavior of the interlocking guide elements, and produces a seizing action. The result is a significant reduction of the indication accuracy. The exposed arrangement of support springs of the indicator apparatus in a non-enclosed housing, and the possibility of dirt getting on the slides, are other potential causes of failure, and thus represent significant disadvantages.